Northumberland has 2 different meanings across 2 categories:
the northernmost county of England; has many Roman remains (including Hadrian's Wall)
"Visiting Northumberland, tourists can explore ancient Roman ruins and walk along the historic path of Hadrian's Wall."
The most northerly county of England bordered by County Durham, Cumbria, Tyne and Wear, Scotland and the North Sea.
"Visitors often flock to Northumberland to explore its rugged coastline along the North Sea while staying within the historic borders that separate it from County Durham and Scotland."
The name comes directly from Old English and originally meant "the land of the Northumbrians." It entered modern usage as a straightforward reference to that specific region in northern England.